Japanese Patent Publication No. 2002-18744 A discloses a power tool management system which is designed to generate maintenance information prompting a user to make a suitable maintenance when a cumulative use of the power tool satisfies a predetermined criterion. The system includes a management unit which is provided as a separate entity from the power tool and is configured to give the criterion to the power tool by means of a radio transmission. The management unit is also configured to set one of predetermined operation modes, one being a normal mode which permits the power tool to operate upon actuation of a power switch, and the other being a disable mode which inhibits the power tool from operating even upon actuation of the power switch. In this sense, the above system can be more or less security-oriented to prevent an unauthorized use of the power tool. However, it is required a rather cumbersome routine to set the power tool in security. That is, each time the power tool is stored, the management unit has to be manipulated to set the disable mode. In addition, it is also required to release the disable mode and set the normal mode each time the authorized user intends to use the power tool. Since there has been reported an increased number of cases of the power tools being stolen, there is a certain demand of realizing an antitheft power tool system without resorting to the cumbersome management as proposed in the above prior art system.